Vietnamese security officers set up a fence outside an area of the Chinese Embassy in Hanoi on May 18. / Na Son Nguyen, AP

by Calum MacLeod, USA TODAY

by Calum MacLeod, USA TODAY

BEIJING - Five ships will join in the evacuation of Chinese nationals from Vietnam after more than 3,000 fled the nation following deadly anti-China riots there last week over a Chinese oil rig deployed in nearby contested waters.

Police and security officers in the Vietnamese capital Hanoi and in southern Ho Chi Minh City halted anti-China protests Sunday, unlike the previous weekend when similar protests were permitted. Authorities in one-party Vietnam rarely allow public demonstrations, but nationalist, China-related protests sometimes prove an exception.

The crackdown Sunday, enforced by thousands of police and security officers, suggests Hanoi wants to avoid further antagonizing its far larger neighbor, despite the official and widespread public anger in Vietnam over recent Chinese moves in the South China Sea, which U.S. officials have also described as "provocative."

Two Chinese workers were killed midweek, and more than 100 injured as mobs targeted Chinese factories and Taiwanese factories employing Chinese workers. In a bid to reassure nervous foreign investors, top Vietnamese security official Lt. Gen. Hoang Kong Tu vowed Saturday to ensure the safety of all foreign citizens and investments in the country, including from China. Over 1,000 suspects have been arrested in connection with the attacks, which authorities have blamed on extremists.

China has increased its security warning for Chinese tourists in Vietnam, and is now telling citizens not to travel to the country, Chinese Foreign Ministry spokesman Hong Lei said in a statement released Sunday. China will also suspend some bilateral exchange plans with Vietnam in response to the violence, Hong said.

While China and Vietnam are both one-party, nominally socialist states, tensions have long troubled their relationship. Vietnamese remain highly suspicious of their giant neighbor, with whom they fought a border war in 1979. An earlier clash, in 1974, gave China de facto control of the Paracel Islands, where China towed a mobile, deep-sea oil drilling rig on May 1.

That move sparked the latest troubles and highlighted Beijing's increasingly assertive approach to its territorial claims that cover almost the entire South China Sea, one of the world's busiest waterways that is potentially rich in oil and gas. China now has several maritime disputes simmering with countries nervous about Beijing's growing economic and military power.

Vietnam says 80 Chinese ships are protecting the oil rig, deployed some 120 miles from Vietnam's coast and therefore well within Vietnam's 200-mile exclusive economic zone, as defined by the U.N. Convention on the Law of the Sea. Both sides have accused the other of "provocations" as boats have collided, and Chinese ships have used water cannons, according to Vietnamese media footage.

"As long as the oil rig is not withdrawn from Vietnam's continental shelf, the Vietnamese people will continue to demonstrate, and their emotions will continue to be angry and sensitive," Le Dang Doanh, a Vietnamese economist and former government adviser in Hanoi, said Friday. "Vietnamese people want to keep peace, but it would be a miscalculation to take that as weakness."

The U.S. government usually takes no stand on the region's various sovereignty disputes, but Vice President Joe Biden and other top U.S. officials told a top Chinese general visiting the USA last week that Beijing's behavior in the maritime disputes was "dangerous and provocative" and must stop, a senior U.S. official told the Reuters news agency Thursday.

Meanwhile, Beijing thinks Washington should stay out of the conflict and shows no intention of withdrawing the rig. General Fang Fenghui, chief of the general staff of the People's Liberation Army, said Thursday in Washington that China would continue drilling for oil in what he called China's territorial waters. Fang blamed Hanoi for the stand-off, criticized President Obama's strategic "pivot" to Asia and said China cannot afford to "lose an inch" of territory, Reuters reported.